This invention relates to spool-type cartridges or cassettes, and more particularly to such cartridges or cassettes for spooled web material, such as photosensitive material or recording media in web form. The invention is more particularly directed to a low cost and effective single-use spool locking arrangement by which one or more of the spools of web material are positively retained against rotation during shipping and handling, which lock is released when the cartridge or cassette is inserted into a suitable utilization apparatus.
Spool locks for spools of web material in cartridges and/or cassettes have generally been of two types. A first type consists of a reusable or two way lock. Such locks commonly have a pivotally mounted latch member which is movable out of engagement with the spool when the cartridge or cassette is inserted into the utilization apparatus, as by the interengagement of an operating member on the using equipment. Normally a spring, or other return mechanism, cause re-engagement of the latch member hen the cartridge or cassette is removed from the equipment. Such retaining mechanisms are usually relatively costly and complicated and are more commonly employed with reusable two spool cassettes.
A second spool lock consists of the "one-shot" or single use frangible connection between the spool and the body of a single-use cartridge. A sufficiently high withdrawal tension on the web material, transmitted by the spool to the connection, causes the failure of the connection. These arrangements are not unlike a fuse, in that they must lock the spool with sufficient force to resist anticipate loads during transit and the like, but must also be dependably breakable to provide for the paying out or withdrawal of the web under normal handling tensions. The design of such frangible connections requires a careful balance between holding torques and ease of release by web withdrawal.
A further disadvantage of releasable or frangible cartridge spool retainers is that they have been generally designed for retaining relatively light-weight reels and spools, and such compromise between holding force and ease of release is more difficult to make with spools that have a large inertia. Therefore, such designs are not well suited for the securing of relatively heavier rolls of web type media material.
A need exists for a low cost and dependable single retention of the spool during handling, which may be readily and fully removed from service when desired, and which does not involve critically designed components.